Stem cell factor receptor (c-Kit) (c-Kit)

The **stem cell factor receptor**, also known as **c-Kit** or **CD117**, is a type III transmembrane receptor tyrosine kinase encoded by the KIT gene. It serves as the high-affinity cellular receptor for stem cell factor (SCF), a cytokine essential for hematopoiesis, melanocyte function, gametogenesis, and mast cell biology. Structurally, c-Kit features an extracellular domain with five immunoglobulin-like domains responsible for ligand binding and dimerization upon SCF engagement; a single transmembrane segment; a juxtamembrane region that regulates activation; and an intracellular split kinase domain interrupted by an insert sequence. Ligand-induced dimerization triggers autophosphorylation at specific intracellular tyrosines that serve as docking sites for signal transduction proteins containing SH2 domains. This initiates multiple downstream pathways including PI3K/Akt, Src family kinases, PLCγ/PKC pathway, and Ras/MAPK cascade—regulating diverse cellular processes such as survival, proliferation/migration/differentiation depending on context. Gain-of-function mutations in KIT are oncogenic drivers in several human cancers—most notably gastrointestinal stromal tumors—and are therapeutically targeted using small-molecule protein kinase inhibitors like imatinib mesylate. Loss-of-function mutations cause disorders such as piebaldism characterized by pigment loss.

Other names

c-KitCD117KITProto-oncogene c-KitSCF receptor

Inhibition of tyrosine kinase activity by binding to the ATP-binding site of the inactive conformation of c-Kit. Blockade of downstream signaling pathways involved in proliferation and survival.